at the moment pools are estimating that a 4.7Thash miner (costing $1000) would earn you $6 a day.
and at 1300kwh this can cost between $3-$9 in electric which is a +$3 income or a -$3 income depending on electric
based on 10cents per kwh electricif in the UK where electric is 20p(30cent)EDIT. u said you dont pay electric so lets just call it $6 income for todays estimate)
but with a 2 week delivery time that $6(£4) turns into $5.40(£3.60) because of the dynamics of how difficult it becomes to mine changes every 2 weeks
so by the time you get your $1000(£650) piece of equipment and then mine for a 2 week period you will get
$42 based on 10cent electric and bitcoin staying around the $400 mark. two weeks later
$37.80 two weeks later
$34 two weeks later
$30.60 two weeks later
$27 two weeks later
$25 two weeks later
$22 two weeks later
$20 two weeks later
$18
and then the reward halving would occur. so if bitcoin is still priced at $400 each
$8 two weeks later
$7.20 two weeks later
$6.50 two weeks later
$5.85 two weeks later
basically at this point you have made a combined total of under $300 and its been about 6 months.. knowing your income is diminishing every fortnight.
now you may be asking why or how do miners mine for profit.
the answer is simple.
the cost to make a ASIC is only a couple hundred dollars, but they sell them to noobs in the western world for $1000.
meaning for every rig you buy. they hand you one and you have given them 4 for free..
so with electric under $1.50 a day in asia and iceland. the profit they make starts at $63 (and thats pure profit because they dont need to cover costs of the ASIC.
infact thanks to you giving them 4 asics for free when you handed over $1000 they are making $250 a fornight to start with while you will be still waiting for delivery of your 1 asic
which means they can have 9 months of pure profit. before the income becomes the same as electric
while you are only getting 9 months before income becomes under $1 a week and you still have not even got 50% of the initial $10000 cost of your ASIC back.
so in short. mining bitcoin is not for the small consumer hobbyist of the western world. if you are still interested in mining then you should lookinto some altcoins that might have an initial "pump". but in reality the risk does not outweigh the reward
you are far more better off just buying small amounts of bitcoin, maybe $10-$20 a week. and just store it. and let the long term deflationary price increase the value. just dont waste $1000 on a piece of equipment that only gets you 35-50% return